The use of the trimethylsilyl group as an oxygen protecting group in organic synthesis will be pursued. Reactions will be studied in which the ease of solyolysis of the trimethylsilyloxy group will permit functional group synthesis under mild conditions. As an example, drastic and acidic conditions are required to brominate a carboxylic acid. We have found that carboxylic acids converted to dianions and treated with trimethylchlorosilane form bistrimethylsilyl ketene ketals I which can be brominated using bromine under neutral conditions. R2CHCHO2H yields R2C super minus CO2 super minus yields R2C double bond C(OSiMe3) 2 (I) plus Br2 yields R2CBrCO2SiMe3 yields R2CBrCO2H. Trimethylsilyl esters hydrolyze under very mild conditions. Similarly, I and chloramine yield alpha-amino acids.